This invention relates generally to improvements in and to adhesive attachments of the type designed for bonded affixation to a selected substrate, such as an adhesive attachment of the type disclosed in U.S. Pat. Nos. 5,013,391 and 6,773,780 having a bonding surface circumscribing a temporary attachment member which holds the attachment bonding surface against the substrate for the duration of a bonding agent cure time. More specifically, this invention relates to a protective peel-off masking device for overlying a pre-cleaned attachment bonding surface to safeguard the bonding surface against undesired contamination prior to installation onto the selected substrate.
Adhesive bonded attachments are generally known in the art for connecting a selected component such as a threaded nutplate or a threaded bolt onto a selected substrate such as a panel or other frame component in an aerospace or automotive application or the like. Such adhesive attachments typically define a bonding surface adapted to receive a selected curable bonding agent, whereupon the bonding surface is pressed against the selected substrate for the duration of bonding agent cure time. In preferred attachment designs, a temporary attachment member is provided for temporary connection to or engagement with the substrate in a manner functioning to urge or draw the bonding surface firmly against the substrate until the bonding agent is substantially completely cured. As a result, the adhesive bonded attachment is affixed to the substrate with a substantially optimized adhesive attachment force. In one such adhesive attachment design, as disclosed in U.S. Pat. No. 5,013,391 which is incorporated by reference herein, a nutplate assembly includes a threaded nut carried by a nutplate base which defines the bonding surface for adhesive bonded attachment to the substrate. The threaded nut additionally carries a resilient fixture pin having a size and shape to be pulled into and bindingly engage an opening formed in the substrate. This fixture pin thus comprises the temporary attachment member circumscribed by the bonding surface on the nutplate base. The fixture pin functions to draw the bonding surface of the nutplate base firmly against the substrate for the duration of a bonding agent cure time, resulting in strong adhesive attachment of the nutplate base to the substrate. After the bonding agent cures, the resilient fixture pin can be pulled through the substrate opening and separated from the threaded nut. Subsequently, the threaded nut is exposed through the substrate opening for appropriate assembly with a suitable threaded fastener or the like.
In another adhesive attachment design, as disclosed in U.S. Pat. No. 6,773,780 which is also incorporated by reference herein, a threaded fastener such as a headed bolt or screw is carried by a generally annular mounting base defining the bonding surface for adhesive affixation to a selected substrate. In this design, the fastener head comprises the temporary attachment member circumscribed by the bonding surface on the mounting base. The fastener head carries a pressure sensitive adhesive or the like suitable for temporary or impermanent connection to the substrate. The thus-adhered fastener head cooperates with one or more resilient spring-like structures to apply a positive force to the mounting base in a direction pressing the bonding surface thereon against the substrate for the duration of a bonding agent cure time. Once again, this produces a strong adhesive bonded attachment of the mounting base to the substrate, which in turn supports and retains the fastener relative to the substrate.
While such adhesive bonded attachments of the above-described types beneficially secure the nutplate or fastener or other attachment component to the substrate with a strong adhesive bonding force, the actual or empirical bonding force can be adversely impacted by the condition and/or cleanliness of the bonding surface at the time of installation onto the substrate. In this regard, the bonding surface is normally pre-cleaned during product manufacture as by sand blasting and/or surface etching, to remove any particulate debris and further to passivate the bonding surface for optimum subsequent bond strength attachment with the selected bonding agent. However, despite such surface pre-cleaning, some bonding surface materials such as certain metals may exhibit varying degrees of oxidation contamination depending upon the time delay between product manufacture and subsequent installation of the adhesive attachment onto a substrate. Alternately, or in addition, post-production contamination of the bonding surface can be attributable to other factors, such as exposure of the bonding surface to dirt and dust, and/or the course of human handling prior to installation. Any or all of these factors can contribute to a reduced bond strength attachment force between the adhesive attachment and the substrate. To avoid this problem, it has sometimes been necessary to re-clean the bonding surface immediately prior to installation of the adhesive attachment onto the substrate.
There exists, therefore, a need for improvements in and to adhesive bonded attachments particularly with respect to an improved device or method for safeguarding a pre-cleaned attachment bonding surface against undesired post-production contamination in the course of pre-installation shipment, handling and/or storage. The present invention fulfills these needs and provides further related advantages.